There is a continuing effort by draftsmen to improve drafting instruments and techniques to minimize effort in thinking and physical manipulation and to minimize the number and complexity of instruments present on drawing boards for the usual drafting requirements. One common drawing or illustration for which the present invention is particularly suitable is in the drawing of a perspective view.
In constructing a perspective drawing, it is desirable to know the exact location of a vanishing point and be able to return to the vanishing point with a minimum of time and effort each time the ruling blade is moved. In cases where a remote vanishing point is required, the presently used methods of drawing involve the use of perspective charts. These charts in effect only estimate the location of a vanishing point. Their usefulness is limited both dimensionally and by the relatively few angle situations they cover and by their printed lines, which whenever bowed in the printing process, adds another element to cause inaccuracy. Moreover, with perspective charts there is the necessity of using tracing paper and this requires retracing for comprehensive drawing.
It is also desirable to produce a dense black waterproof line that will hold a good reproduction quality after it is erased over and washed over. A dense black waterproof line imposes the use of a higher density ink which because of its viscosity, flows and dries more slowly. This in turn limits its use to select applicator tools. Also a more viscous paint when used to rule a line produces a higher bead on the surface of the paper. These characteristics combine to increase the chances of ink contact between the drawing paper and ruling blade. When a ruling blade contacts a wet bead, the blade will act as an uncontrolled vehicle for escorting ink to unpredictable areas in drawing. This situation is aggravated by the uneven or wavy surface of some types of drawing paper. Time is also an important factor in using dense inks or paint. A slight amount of drying by evaporation exercises too great an influence over higher viscosity ink and this must be overcome by keeping the ink flowing from the applicator tool.
In presently used methods of drawing from a vanishing point, two hands are needed to maneuver the ruling blade into alinement, after which one hand is used to rule and the other hand is used to both stabilize the blade in the sight area and hold to the vanishing point. In the case of a distant vanishing point, the leverage problem becomes acute. To avoid ink or paint contact with the ruling blade, blotters must be repositioned under the blade each time it is moved, unless enough tape is added to the blade to set it away from the surface of the drawing. The time required in these maneuvers is usually enough to allow the ink in the applicator to dry (just enough to prevent ink flow) in which case the tool must be cleaned, new ink added and part of the maneuver repeated. It is this feature which discourages the use of ink that has the best reproduction quality.
It is therefore a desirable accomplishment to be able to rule from a vanishing point in a way that ensures accuracy, that vanishing point must be anchored within the confines of a stable drawing plane or table surface. (Off the table apparatus made of steel rod is subject to deflection at the vanishing points.) Contact between a ruling blade and the drawing paper must be minimized at the ruling edge of the blade and maximized at a safe distance from the ruling edge.
Because large drawing tables are available and simple detachable extensions can be constructed for smaller tables, it is desirable to provide some type of apparatus that will improve existing drafting practices within the limits of a table surface.
Accordingly, it is a general object of this invention to provide a novel and improved drafting system and apparatus.
Another object of this invention is to provide a simple, durable, versatile, efficient and comparatively inexpensive drafting system and apparatus that is particularly effective in returning to vanishing point in a perspective drawing and ruling all lines on a drawing.
Another object of this invention is to provide a drafting system in which a selected point such as the vanishing point in a perspective drawing may be anchored within the confines of a drawing plane or table surface to insure drawing accuracy.
Still another object of this invention is to provide a novel ruling blade characterized by a minimum contact between the ruling edge and the drawing paper and maximized a safe distance from the ruling edge.
Still a further object of this invention is to provide a drafting system that is usable on smaller drafting tables and larger drawing tables with detachable extensions in such a way that it allows a conformable angle to the drawing surface, occupies only the table area needed to reach the vanishing points with accuracy and does not impose added inconveniencies over existing practices.
Yet another object of this invention is to provide a drafting system that allows:
a. reaching and anchoring to vanishing points that are considered remote but within the confines of a drafting surface;
b. a steeper, more comfortable working angle to the drawing surface;
c. returning to and ruling from vanishing points in a way that is not subject to ruling deflection in the sight area or binding at the vanishing points;
d. keeping the drawing area relatively free from friction surface, smudge producing and sight interferring apparatus in excess of that is needed for a particular line or lines in a drawing;
e. ruling with a wide range of scribing instruments, inks and paints.
Another object of this invention is to provide improved drafting system that minimizes the amount of apparatus on a board, minimizes physical manipulation and is particularly effective in accurately drawing perspective views.
Still another object of this invention is to provide novel drafting apparatus having an edge pivoted ruling blade that allows the drawing of a perspective line to the vanishing point.
Another object of this invention is to provide novel drafting apparatus and system characterized by the provision of an upright pivot pin at a selected point on a drawing board such as at a vanishing point and a ruling blade having a ruling edge and a pin hole or slot receiving the pin whereby the ruling blade is edge pivoted.
Still another object of the present invention is to provide a drafting system in which a pair of T-square like reference heads are removably attached to a grooved ruling blade and referenced to the vanishing points to draw vertical lines and wherein the T-square like heads and blades also provide a T-square function.